Quantum Anti-Zeno Effect in Artificial Quantum Systems

In this paper, we study a quantum anti-Zeno effect （QAZE） purely induced by repetitive measurements for an artificial atom interacting with a structured bath. This bath can be artificially realized with coupled resonators in one dimension and possesses photonic band structure like Bloeh electron in a periodic potential. In the presence of repetitive measurements, the pure QAZE is discovered as the observable decay is not negligible even for the atomic energy level spacing outside of the energy band of the artificial bath. If there were no measurements, the decay would not happen outside of the band. In this sense, the enhanced decay is completely induced by measurements through the relaxation channels provided by the bath. Besides, we also discuss the controversial golden rule decay rates originated from the van Hove＇s singularities and the effects of the counter-rotating terms.     

Effects of SiNx on two-dimensional electron gas and current collapse of A1GaN/GaN high electron mobility transistors

SiNx is commonly used as a passivation material for AlGaN/GaN high electron mobility transistors (HEMTs). In this paper, the effects of SiN x passivation film on both two-dimensional electron gas characteristics and current collapse of AlGaN/GaN HEMTs are investigated. The SiNx films are deposited by high- and low-frequency plasma-enhanced chemical vapour deposition, and they display different strains on the AlGaN/GaN heterostructure, which can explain the experiment results.     

Multiple-bipolar-tap tunable spectrum sliced microwave photonic filter

A spectrum sliced microwave photonic signal processor structure, which is all-fiber based and features simplicity, together with the ability to realize tunability, reconfigurability, bipolar taps, and multiple-tap rf filtering, is presented. It is based on thermally controlled optical slicing filters induced into two linearly chirped fiber Bragg gratings. Experimental results demonstrate the realization of versatile microwave photonic filters with frequency tunable, reconfiguration, and bipolar-tap generation capabilities.     

Persistence and breakdown of Airy beams driven by an initial nonlinearity

We study the behavior of Airy beams propagating from a nonlinear medium to a linear medium. We show that an Airy beam initially driven by a self-defocusing nonlinearity experiences anomalous diffraction and can maintain its shape in subsequent propagation, but its intensity pattern and acceleration cannot persist when driven by a self-focusing nonlinearity. The unusual behavior of Airy beams is examined from their energy flow as well as the Brillouin zone spectrum of self-induced chirped photonic lattices.     

Graphene field-effect transistors with ferroelectric gating

Recent experiments on ferroelectric gating have introduced a novel functionality, i.e., nonvolatility, in graphene field-effect transistors. A comprehensive understanding in the nonlinear, hysteretic ferroelectric gating and an effective way to control it are still absent. In this Letter, we quantitatively characterize the hysteretic ferroelectric gating using the reference of an independent background doping (n(BG)) provided by normal dielectric gating. More importantly, we prove that n(BG) can be used to control the ferroelectric gating by unidirectionally shifting the hysteretic ferroelectric doping in graphene. Utilizing this electrostatic effect, we demonstrate symmetrical bit writing in graphene-ferroelectric field-effect transistors with resistance change over 500% and reproducible no-volatile switching over 10? cycles.     

One phonon resonant Raman scattering in a quantized spherical film

We have presented a theoretical calculation of the differential cross section (DCS) for the electron Raman scattering (ERS) process associated with surface optical (SO) phonon modes in a semiconductor quantized spherical film. We consider the Fröhlich electron–phonon interaction in the framework of the dielectric continuum approach. We study the selection rules for the processes. Singularities are found to be size-dependent and by varying the size of the QDs, it is possible to control the frequency shift in the Raman spectrum. A discussion of the phonon behavior for the films with large and small size is presented. The numerical results are also compared with that of experiments.     

Fe valence state at the surface of the Fe0.5Cu0.5Cr2S4 spinel

Here we present X‐ray absorption measurements of a vacuum cleaved Fe_0.5Cu_0.5Cr₂S₄ single crystal. Measurements at different positions on the cleaved sample surface clearly reveal a difference between the valence state of the Fe ions in the sur‐ face layers and the valency of the Fe ions present in the bulk. These results confirm the findings of recent measurements outlined previously. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

HL-2A装置的约束改善和边界净输入功率分析

在HL-2A装置孔栏位形放电的等离子体实验中,电子回旋辅助加热期间观察到了等离子体约束改善的现象,并对等离子体从低约束模式(L模)向约束改善模式转换时的等离子体线平均电子密度、等离子体储能、分界面内辐射功率、能量约束时间、H_α辐射等进行了研究。同时,分析了电子密度和等离子体辐射功率的空间分布随时间的演化。对改善约束的相关功率(辅助加热、欧姆加热功率和损失功率)进行了分析,并研究了等离子体约束改善转换时的边界净输入功率(阈值)与电子线平均密度和环向磁场的关系。     

SUNIST装置中磁探针出气率测量

通过出气率测量装置评价了SUNIST装置的内部磁探针出气特性,实验结果表明其出气量和出气气体成分不足以影响SUNIST真空特性。其后的放电实验验证了这一结论。     

有机薄膜电致发光器件工艺检测的一种简便方法——覆膜加热观测法

提出了一种简便易行、并与有机薄膜电致发光器件制备工艺完全兼容的工艺检测方法－－覆膜加热观测法。这种方法是在器件的制备工艺过程中,同时在铟锡氧化物（ITO）电极的各层有机薄膜上覆盖一层不透气的薄膜（如金属Al膜等）,接着进行快速加热,最后对器件表面进行形貌观测。采用这种方法,观察了器件表面气泡的形成过程,观察了加热温度、ITO表面处理以及有机物纯度对敢泡形成的影响。实验表明,覆膜加热观测法能有效地对工艺进行对比检测,从而达到改进工艺、提高器件质量的目的。